Olympic double sculls gold medallist Nathan Cohen may be the obvious choice to replace Mahe Drysdale in the single scull but the Southlander says he is keen to remain part of a team.

Cohen was the fastest in the heats of the men's premier single sculls at the national championships on Lake Ruataniwha at Twizel on Tuesday but said he wanted his future to be in a quad.

"I've stated I'd like to be part of a quad because it keeps things fresh and it's a new challenge."

Cohen supported Michael Arms or Robbie Manson filling Drysdale's spot. Ironically, both men were part of the New Zealand quad in London.

Drysdale is taking a six-month hiatus from rowing, leaving an opportunity for a new sculler to impress at three World Cup regattas before his return in August.

Cohen said that after his first long holiday in 10 years he was not in the best shape, but he was pleased to get back into a rhythm after the euphoria of his gold medal with Joseph Sullivan in London.

"I've only been back in serious training for the last four weeks so timing-wise the nationals may not be perfect but it's good to spend a week in Twizel and get on the water and give back to the public who have been so good to us."

He said despite coach Dick Tonks' new focus being on the women's crews, the training routines would remain for the men and it was up to each individual to ensure they maintained the standards of the past.

"He's set the standard in terms of training and preparation and mental grit, so we have to maintain his standards. He'll still be around Lake Karapiro which is good news for everyone."